1. Field of the Invention
A liquid membrane process for removing ions from solution which comprises contacting a solution containing a first ion and a second ion with an emulsion, said emulsion comprising an external phase which is immiscible with said solution and contains a first complexing agent, and a second complexing agent, said first complexing agent being capable of forming a first complex with said first ion, and said second complexing agent being capable of forming a second complex with said second ion, both of said complexes being soluble in said external phase, and an internal phase, which comprises a (1) decomplexing agent, said decomplexing agent being capable of converting said first conplex into said first complexing agent and said first ion and (2) an inhibiting agent which is capable of inhibiting the formation of said first complex, whereby the first ion diffuses from said solution into said internal phase, and said second ion diffuses from said solution into said external phase.
Preferably, the ions are metal ions - for example, the first ion may be selected from the group consisting of magnesium, calcium, iron, aluminum or any mixture thereof, and said second ion may be uranium. The metal ion may be in either a cationic or anionic form. The complexing agents are generally oil-soluble ion-exchange compounds such as, for example, pyrophosphates, carboxylates, amines, oximes, etc., which are insoluble in the aqueous solution.
2. Description of the Prior Art
The removal of specific ions or compounds from dilute solutions and concentrating them in another solution is desirable in many metallurgical and waste water treating processes. Generally the dilute solution is aqueous in nature. Processes for such removal, which have been used, include the following:
1. Extraction of the ions or compounds into water immiscible phase which may contain a complexing or ion exchange agent followed by reextraction into another aqueous phase.
2. Liquid membrane permeation with a membrane which allows permeation of the specific ions or compounds in one form, followed by reaction with a dissolved chemical encapsulated as an aqueous phase inside the membrane so as to convert the permeating ions or compounds into a nonpermeating species, i.e. by neutralization or precipitation. See, for example, U.S. Pat. Nos. 3,617,546, and 3,779,907.